Method of preparing phonograph recordtn



(N-O Model.)

T. A. EDISON.

METHOD OF PREPARING PHONOGRAPH RECORDING. SURFACES.

No. 393,465. Paltented Nov. 27, 1888,

UNITED STATES THOMAS A.

PATENT OFFICE.

nnisonos LLEWELLYN PARK, NEW JERSEY, ASSIGNOR 'ro THE EDISON PHONO GRAPH'COMPANY. OF NEW JERSEY.

SPECIFICATION forming part of Letters Patent No. 393,465. dated November27', 188 8.

Application filed July I, 1888.

'To all whom, it may concern:

specification.

In my phonograph I employ a removable phonogram-blauk having arecording-surface of a yielding material. 'I prefer to use a wax or awax composition for the purpose, and I also prefer tomake the entireblauk of the'wax or waxcomposition. These blanks after he- 'ing mountedin the machine have their recording-surface turned true by a knife whichis. carried by the rocking holding-arm and 'the point of which ispreferablyiu close proximity to the recording-point. The blanks-usedwith" my machine are also preferably adapted to. have. their surfacesturned ofi by thissame cutting-tool for the purpose of using them anumber of times, an old record being removed to make place for a newone.I have heretol'orc employed as the cutting-tool a knife with itscutting-edge parallel with the axis of the phonogram-eylinder andpractically at right angles to the track of record. Ilhave discoveredthat wax and similar yielding materials, by reason of their elasticityand the cohesion of the particles, are not turned off smoothly by thetool, but that microscopic cracks or breaks in the surface are formedwhich are parallel with the .edge of thecutting-tool. To these cracks orbreaksI attribute, in a measure, the production of foreign sounds by therecord. These cracks or breaks are not as deep as the track made by therecording-point, but since the recording-point meets at the one time theresistance due to material of the full depth of its incision and atanother time(when crossing a crack or break in the surfacela lc'sserbody of material I have found that the record produced iscorrespondingly affected, having irregularities causing false vibrationsin the reproducer. I have found that the effeet of these cracks orbreaks is greatly modified and the trouble arising from them largelyovercome by so cutting or turning 05' the surface of the blank that thecracks will beob- Serial I10. 279,393. (No model.)

cording-point. The improved effect, I think, is due to the fact thatwhen the cracks are oblique the recording-point does not meet the crackacross-the full width of its advancing -edge at one time, but onlyacross a portion of such edge,andthedisturbauce is more grad:

ha] and is extendedovera greater time.

In the accompanying drawings, forming a part'hereof, Figure 1 is avertical transversesection of a phonograph provided with a turning-oiltool; Fig. 2, aview showing the phonogram-blank being cut by the tooland illustrating the relative positions of the cuttingtool and therecording-point; and Figs. 3 and 4 are views onan exaggerated scaleshowing the relation between the recording-poi nt of the phonograph. andthe cracks in the recordingsurface.

A is the revolving phonogram-cyl i ndcr', having the W3. phon gra-mblank B carried thereby.- v v G is the rocking holding-arm carrying therecorder D and thecutting-tool E. This toolis a knife mounted on the endof a lever, F,

pivoted to the arm 0. The end of the lever F'in rear of the pivot passesover'the head of an adjusting-screw, a, while a spring, 7), draws itdownwa'rdly against said-screw. The point of-the knife E is oblique, asshown in Fig. 2, the cracks produced inthe wax recording-surface by itbeing oblique to the track of record made by the point a of therecorder.

In Figs. 3 and iris-shown in horizontal section the 'recording-point'c,while d represents the cracks in the recordingrsurface. If those cracksare parallel with the advancing edge of the recording-point, asshownin-Fig. 3, the 'recordingpoint will meet the cracks at the:same'time'across the full width of its advancing'edge, while if thecracks are oblique, as in Fig. 4, only aportioinof the advancing edge ofthe recordingpoint'will be in the crack at any one time, and thedisturbing eficct of the crack will be distributed over a greater spaceof time, and hence will be more gradual.

It will be understood that the cutting-tool isto' be used eitheralternately with the recorder or simultaneously therewith. In the lattercase the cutting'tool is placed somewhat in advance of therecording-pointin the direction of longitudinal mo ement of said point,as is illustrated in Z.

I do not claim in this application the recording-point and cutting-tooladapted to be operated simultaneously, this being claimed in myapplication filed May 29, ll88 8, Serial No. 275,441.

In my application No. 784, Serial No. 279,322, filed'July 7, 1888, Ihave claimed the phonograph provided with a turning-oil tool having acutting-edge oblique to the track of record. This application relates tothe method of preparing phonograph recording-surfaces by means of anoblique cutting-edge. It is obvious that the method might be carriedinto effect without mounting the cutting-tool upon the phonographitself, since such tool might be employed in any suitable machine, suchas 20 a lathe or any modification of a lathe.

What I claim is-- v 1. The method of preparing phonographrecording-surfaces, consisting in turning 011 such surfaces by a toolhaving a cutting-edge acting 25 obliquely to the track of record,substantially as set forth. I

2. The method of preparing phonograph rcco1 ding-surfaces of wax or awax composition, consisting in turning off such surfaces by atool 30having a cutting-edge acting obliquely to the track of record,substantially as set forth.

This specification signed and witnessed this 30th day of June, 1888.

THOS. A. EDISON. Witnesses.

WILLIAM PELZER, A. W. KIDDLE.

